Emerson unidrive m200 - Change to Maximum Drive Switching Frequency at Low Output Current; Voltage Shelving Disable; Low Frequency Torque Adjustment

Parameter 05.081 Change to maximum drive switching frequency at low output current
Short description Change to maximum drive switching frequency at low output current
Mode Open‑loop
Minimum 0 Maximum 1
Default 0 Units
Type 1 Bit User Save Update Rate Background read
Display Format Standard Decimal Places 0
Coding RW
If the user has selected a maximum switching frequency in the range 2kHz to 6kHz, setting this parameter will cause the drive to switch to maximum switching
frequency at low output currents.
Swaps to 16kHz if the output current magnitude is less than 30% (Frame sizes 1-4) and 20% (Frame sizes 5 and above) of drive OI.AC level for a period
longer than 100ms.
Swaps back immediately if the output current magnitude increases above the defined levels by more than 5%.
The original switching frequency may still be under the control of the inverter thermal model. This feature is disabled if the thermal model or user has changed
the switching frequency within the last 10 seconds.
Parameter 05.083 Voltage Shelving Disable
Short description Set to 1 to only measure the d.c. link voltage when the inverter is inactive
Mode Open‑loop
Minimum 0 Maximum 1
Default 0 Units
Type 1 Bit User Save Update Rate Background read
Display Format Standard Decimal Places 0
Coding RW
When this parameter is 1, the DC link voltage will only be measured when the inverter is inactive. The DC link voltage readings are filteredusing a 128ms
filter and the average value stored for use when the inverter becomes active.
This stored value is used instead of the actual measurement when the output voltage demand is converted to a modulation index.
This removes the dc bus voltage forward compensation. It will also remove the effects of “oscillation” experienced when the drive is supplied by an extremely
soft supply of through a high inductance filter.
Parameter 05.084 Low Frequency Torque adjustment
Short description
Controls the boost level of the slip frequency when the output frequency is below one third of the rated
frequency.
Mode Open‑loop
Minimum 0.0 Maximum 100.0
Default 0.0 Units %
Type 16 Bit User Save Update Rate Background read
Display Format Standard Decimal Places 1
Coding RW
This parameter can be used to modify torque at low output frequencies in one of three different ways:
1) Slip boost
Used in resistor compensation (Ur) modes, Open-loopVoltageMode (05.014) set to 0, 1, 3, and 4.
The slip frequency (see MotorRatedFrequency (05.006) is modified when the output frequency is below one third of the motor rated frequency to provide a
torque boost.
The modification consists of an addition to the calculatedslipfrequency controlled by the user parameter LowFrequencyEstimatorThreshold,
LowFrequencyTorqueadjustment (05.084) . The addition is equal to LowFrequencyEstimatorThreshold,LowFrequencyTorqueadjustment (05.084) x
calculatedslipfrequency at zero Hz, falling linearly to 0.0% at one third of the motor rated frequency. e.g. if this parameter is set to 100%, the slip at 0Hz for
ratedtorqueproducingcurrent would be ratedslip+ratedslip or 2xratedslip.
2) Voltage boost
Used in resistor compensation (Ur) modes, Open-loopVoltageMode (05.014) set to 0, 1, 3, & 4, and slip compensation has been disabled
(see MotorRatedFrequency (05.006) ).
The amount of stator resistor compensation is modified when the output frequency is below one tenth of the motor rated frequency to provide a torque boost.
The modification consists of an addition to the calculatedstatorresistorcompensation controlled by the user parameter LowFrequencyEstimatorThreshold,
LowFrequencyTorqueadjustment (05.084) . The addition is equal to LowFrequencyEstimatorThreshold,LowFrequencyTorqueadjustment (05.084) x
calculatedstatorresistorcompensation at zero Hz falling linearly to 0 at one tenth of the motor rated frequency. e.g. if this parameter is set to 100%, the stator
resistancecompensation at 0Hz would be calculatedstatorresistorcompensation +calculatedstatorresistorcompensation or 2xcalculatedstatorresistor
compensation .
3) Slip taper
This feature is used in fixed boost tapered mode (Open-loopVoltageMode (05.014) set to 6) to taper the slip limit back to zero at 0Hz. The taper start point is
defined as LowFrequencyEstimatorThreshold,LowFrequencyTorqueadjustment (05.084) x MotorRatedFrequency (05.006) / 100. See Open-
loopVoltageMode (05.014) for a detailed explanation.
Unidrive M200 Parameter Reference Guide
Issue: 01.05.00.10
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